1. Field of the Invention
The present invention relates to a backlight unit to be disposed on the back of a liquid display panel or the like.
2. Description of the Related Art
A backlight unit comprises a light guiding module (“flight guiding module” is also called “backlight”) and a resin flame which houses the backlight. The backlight unit is disposed on the back of a display panel, such as liquid crystal display, so that the light from the light guiding module is provided to a display area of the display panel.
Japanese patent publication JP2000-75273A discloses a backlight unit comprising a metal frame provided on a display panel side of a resin frame, for the purpose of increasing the strength of the resin frame. The metal frame is formed substantially in a box shape. The upper flat surface (or plane) of the metal frame has an opening formed in an portion corresponding to a display area of the display panel so that light from a light guiding module can pass therethrough.
By fitting the resin frame and the metal frame with each other, a structure having high strength against twisting around diagonal is achieved In addition, display panel positioning spacers formed from a resin are provided on corners of the metal frame, which makes it possible to align the display panel and the metal frame.
In case the positioning spacers formed from resin are provided on the metal frame, however, the positioning spacers may come off from the metal frame during use in an environment that undergoes sharp temperature changes, due to impact and/or the difference in thermal expansion coefficient between different materials.
In case positioning spacers formed from a metal are provided on the metal frame, on the other hand, the display panel may be damaged (e.g. scratched) by the positioning spacers formed from metal during manufacture and use, because metal is tend to be stiffer than the material used in the display panel.
The present invention provides a backlight unit that can maintain high reliability, such as avoiding coming off a spacer and damaging a display panel by a spacer, even when used in a harsh environment such as undergoing sharp temperature changes.